[AR] Re: supersonic retro (was Re: Re: Falcon 9 flight today)

  • From: "Robert C Steinke" <rsteinke@xxxxxxxxxxx>
  • To: <arocket@xxxxxxxxxxxxx>
  • Date: Wed, 02 Oct 2013 12:49:37 -0600

On Wed, 02 Oct 2013 10:57:11 -0700
 David Masten <dmasten@xxxxxxxxxxx> wrote:

On 10/2/2013 10:32 AM, Henry Spencer wrote:

On Wed, 2 Oct 2013, Aplin Alexander T wrote:

Musk pointed out during the post-flight Q&A that "I believe the first
time that any rocket stage has attempted to do a supersonic
retro-propulsion." Apparently it was successful (this was the 1st
stage's initial 3-engine re-entry burn).

If you interpret "retro-propulsion" in the specific sense of firing main
engines forward while still in detectable atmosphere, yeah, I think
that's true.  Kistler was going to do it, but they never flew.  Nor did
the shuttle ever do an RTLS abort.
My understanding is that the concern is over the dynamics of the engine startup in the presence of strong shocks. From what I've seen and heard, SpaceX lit the engines well above any appreciable atmosphere. 

Dave
I think they are also worried about aerodynamic instability when flying through the turbulent remnants of the exhaust plume.

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